Research has consistently identified parental monitoring, the extent to which a parent tracks the activities and location of their youth, as an important risk factor for early substance use, delinquency and risky sexual behavior (Crouter &Head, 2002). The literature suggests that parental monitoring may be part of a transactional process between parents and youth and may reflect parent actions such as supervision (e.g., an adult is present to observe youth activities), parental solicitation (e.g., parent attempts to ask youth for information) and child disclosure (e.g., youth decisions to share information with their parents). Measurement issues have made it difficult to identify which specific parent and youth actions are protective, how parent and youth monitoring behaviors work together to influence youth risk, how monitoring strategies change over adolescence, and how parental monitoring and youth disclosure are related to other protective parenting practices (Stattin, Kerr, &Tilton-Weaver, in press). The proposed study aims to further our understanding of the protective process that underlies the association between parental monitoring and risky behavior during middle school. Using latent class analysis, this project will identify unique profiles of monitoring and explore how these profiles are associated with the prevention of early adolescent substance use, delinquency, and deviant peer associations. Specific aims are to (1) Identify latent classes of families who have unique monitoring profiles, explore if these classes are the same across gender of the child, and investigate how youth risky behavior and other aspects of parenting predict membership in these latent classes at the entrance to middle school and (2) Model the stability and change of membership in monitoring latent classes over the middle school period and how youth risky behavior and the affective quality of the parent-child relationship may predict these transitions. The data for the research are from the PROSPER project, a NIDA funded large-scale effectiveness trial of substance use prevention in small towns and rural communities in two states. Data will include measures of monitoring activities reported by mothers and youth from Grade 6 to Grade 9. The monitoring process during middle school may be particularly important for prevention, as early initiation of risky behavior has been linked to later severe antisocial behavior and adult substance abuse (Grant &Dawson, 1997;Dewit et al., 2000;Nagin &Tremblay, 2001). Identifying the specific combinations of monitoring activities that prevent early adolescent substance use may help the field refine the targets of change in family based prevention programs, thus enhancing the efficacy of such programs.